UNIVERSITY  OF  CALIFORNIA  agricultural  Experiment  Station 

BENJ.    IDE    WHEELER.    PRESIDENT 

COLLEGE    OF    AGRICULTURE  thomas  forsyth   hunt,  dean  and  director 

___„_.     _v  H.     E.     VAN      NORMAN,    VlCE-DlR  ECTOR    AND    DEAN 

DEnl\cLtY  University    Farm    School 

CIRCULAR  No.  119 

(September,  1914) 

WINERY   DIRECTIONS 

BY 
FREDERIC   T.    BIOLETTI 


Three  improvements  in  the  methods  of  fermenting  wine  are  being 
adopted  very  widely  in  Californian  cellars.  These  are :  the  nse  of 
snlfnrons  acid,  of  pure  yeast,  and  of  cooling  devices. 

Many  inquiries  are  received  at  the  Station  as  to  the  proper  methods 
of  apptying  these  improvements,  and  some  failures  have  been  reported 
in  their  use.  These  failures  seem  to  be  due  to  mistakes  in  the  times, 
quantities,  or  methods  of  application.  The  following  directions  are 
intended  to  prevent  these  mistakes.  They  are  intended  for  expert 
wine-makers,  who  understand  the  general  processes  of  wine-making, 
and  who  wish  to  improve  their  product  by  the  use  of  these  modern 
methods. 

More  detailed  directions  and  some  of  the  experiment  work  on 
which  these  directions  are  based  will  be  found  in  the  following  publi- 
cations of  the  California  Agricultural  Experiment  Station : 

Bulletin  174 — A  New  Wine-Cooling  Machine. 

Bulletin  213— The  Principles  of  Wine-Making. 

Bulletin  230 — Enological  Investigations. 

These  may  be  obtained  on  application  to  the  Director  of  the  Agri- 
cultural Experiment  Station,  Berkeley,  California. 

DIRECTIONS  FOR  THE  PRODUCTION  OF  YEAST  STARTERS 

A  yeast  starter  is  a  small  quantity  of  vigorously  fermenting  must, 
which  is  mixed  with  the  crushed  grapes  or  defecated  must  to  start 
fermentation. 

Its  uses  are  to  prevent  unfavorable  fermentations,  to  insure  the 
presence  of  a  good  yeast,  and  to  save  time  by  hastening  the  fermen- 
tation. 

Natural  Starters. — Must  taken  from  a  vat  which  is  undergoing  a 
satisfactory  fermentation  may  be  used  as  a  starter.  If  taken  too  near 
the  beginning  of  the  fermentation,  it  will  contain  a  large  proportion 
of  undesirable  forms  of  yeast.     If  taken  too  near  the  end,  the  good 


yeast  may  be  weakened  and  the  must  may  contain  many  harmful 
bacteria.  The  best  time  to  take  the  starter  is  after  half  of  the  sugar 
has  disappeared  but  before  it  has  all  gone  and  before  the  fermentation 
shows  signs  of  weakening. 

Pure  Yeast  Starters. — A  pure  yeast  starter  is  one  prepared  from 
a  yeast  of  tested  qualities  and  is  more  reliable  than  a  natural  starter. 
Cultures  of  pure  yeast  are  supplied  by  the  California  Agricultural 
Experiment  Station  at  Berkeley  at  a  nominal  cost. 

A  starter  is  made  from  the  culture  by  increasing  the  amount  of 
yeast  to  the  required  volume  by  the  following  means : 

1.  Increase  to  one  pint  with  sterilized  must  supplied  with  the 
culture.     About  48  hours  needed. 

2.  Increase  to  21/o  gallons  with  sterilized  must  prepared  at  the 
winery.    About  48  hours. 

3.  Increase  to  40  gallons  with  defecated  must  prepared  at  the 
winery.     About  48  hours. 

The  following  are  detailed  directions  of  how  to  proceed  at  each 
step: 

1.  Two  flasks  will  be  received  from  the  laboratory,  one  marked 
"Yeast"  and  the  other  "Must". 

A  little  alcohol  should  be  poured  on  to  the  cotton  stoppers  of  each 
bottle  and  ignited.  This  will  destroy  mold  spores  present.  The  stop- 
pers are  then  removed  and  the  must  poured  into  the  yeast  flask,  which 
should  be  immediately  closed  with  the  stopper  and  placed  in  a  warm 
place  (as  near  85°  F.  as  is  practicable)  and  allowed  to  remain  until 
in  vigorous  fermentation. 

2.  When  the  yeast  in  the  flask  is  fermenting  vigorously,  fifty 
pounds  of  clean,  cold,  fresh  grapes  are  crushed  and  the  juice  extracted. 
The  grapes  need  not  be  very  ripe — from  17°  to  20°  Bal.  is  favorable. 
All  materials,  buckets,  hoses,  etc.,  that  come  in  contact  with  the  grapes 
or  must  should  be  washed  with  boiling  water  immediately  before  using. 
About  2i/o  gallons  of  must  should  be  obtained  in  this  way.  This 
should  be  heated  to  boiling,  cooled  and  thoroughly  aerated  by  long 
shaking  in  a  five-gallon  demijohn. 

When  the  yeast  in  the  flask  is  in  full  fermentation  it  should  be 
poured  into  the  sterilized,  cooled,  and  aerated  must  in  the  five-gallon 
demijohn,  which  should  then  be  placed  in  a  warm  place,  until  it  is 
in  strong  fermentation.  The  yeast  should  be  added  to  the  2%  gallons 
of  must  the  same  day  that  this  must  is  prepared. 

3.  Obtain  40  gallons  of  must  from  clean,  fresh,  cold  grapes  not  too 
ripe.  Place  this  in  a  thoroughly  cleaned  fifty-gallon  barrel  and  add 
2  ounces  of  potassium  mcta-bi-sulHte.  first  dissolved  in  water.     Allow 


to  settle  24  hours.  Draw  off  the  clear  must  into  a  half  puncheon, 
small  vat,  or  open  fifty-gallon  barrel. 

Thoroughly  aerate  this  clear  must  in  the  vat  by  repeatedly  dipping 
up  a  bucketful  and  pouring  it  back.  Meanwhile  heat  a  portion  of  the 
must  nearly  to  boiling  and  mix  it  with  the  cool  must  in  the  vat.  The 
mixture  should  have  a  temperature  of  about  80°  F. 

Add  the  strongly  fermenting  must  from  the  five-gallon  demijohn 
to  the  aerated  and  warmed  must  in  the  vat  and  cover  with  a  cloth  to 
keep  out  dust  and  maintain  the  heat.  Aerate  three  or  four  times  a 
day  until  the  fermentation  is  going  well. 

When  half  the  sugar  has  fermented  out,  the  must  is  ready  to  use 
as  a  starter.  The  40  gallons  are  enough  to  start  a  vat  containing  10 
or  12  tons  of  grapes. 

Maintenance  of  the  Starter. — The  simplest  method  is  to  start  a 
large  vat  with  the  starter  obtained  as  above  and  to  start  later  vats 
from  this  one.  New  vats  are  thus  started  from  older  vats  in  full 
fermentation,  as  already  described  for  natural  starters.  This  method 
has  been  found  very  satisfactory  in  many  wineries  and  can  be  recom- 
mended where  most  of  the  grapes  received  are  in  good  condition. 

For  wineries  which  receive  grapes  from  long  distances,  especially 
by  rail,  it  is  better  to  install  a  simple  pure  yeast  apparatus  such  as 
that  described  on  pages  72  to  86  of  Bulletin  230,  above  referred  to. 

DIRECTIONS  FOR  DRY  RED  WINE  FERMENTATION 

1.  Filling  Vats. — Vats  should  be  filled  to  not  more  than  four-fifths 
of  their  height.  The  layer  of  crushed  grapes  should  not  be  more  than 
four  feet  deep.  Grapes  should  be  ripe  (about  22°  Bal.)  and  cool 
(about  65°  F.). 

2.  Sulfiting. — Add  potassium  meta-bi-sulfite  during  or  immediately 
after  crushing,  distributing  it  equally  throughout  the  vat.  Use  an 
average  dose  of  8  ounces  per  ton  or  from  6  ounces  to  12  ounces,  the 
larger  amounts  for  very  sweet  grapes  and  hot  weather,  the  smaller 
amounts  for  acid  grapes  and  cool  weather.  The  sulfite  is  conveniently 
used  as  a  solution,  made  by  dissolving  one  pound  of  the  sulfite  in  one 
gallon  of  water.  Half  a  pint  of  this  solution  contains  one  ounce  of 
sulfite. 

3.  Records. — Test  the  Balling  degree  and  the  temperature  of  the 
must  as  soon  as  the  vat  is  filled.  As  soon  as  fermentation  commences, 
these  tests  should  be  made  again  and  repeated  at  least  twice  every 
twenty-four  hours  while  the  grapes  are  in  the  vat.  A  record  of  these 
tests,  showing  the  date  and  hour  made,  should  be  kept  both  in  a  book 
and  on  the  vats  where  they  can  be  referred  to  easily.     This  record  is 


the  wine-maker's  guide.     It  shows  him  how  the  fermentation  is  pro- 
gressing and  when  to  carry  out  the  various  operations. 

4.  Addition  of  Yeast  Starters. — About  six  hours  after  sulfiting, 
add  four  gallons  of  strongly  fermenting  must  to  each  200  gallons,  or 
each  ton,  of  crushed  grapes.  If  the  grapes  are  warm,  the  yeast  should 
be  added  within  three  hours.  Two  gallons  of  yeast  is  sufficient  in  hot 
weather ;  eight  gallons  is  better  in  cold  weather.  The  best  starter  is 
one  taken  from  a  simple  pure  yeast  apparatus  such  as  that  described 
on  page  81  of  Bulletin  230.  Where  this  is  lacking,  use  a  starter  from 
a  vat  in  full  fermentation  in  which  the  sugar  degree  has  fallen  to 
between  4°  and  8°  Bal. 

The  yeast  should  be  well  mixed  by  "punching,"  or  better  by 
"pumping  over." 

5.  Covering. — In  a  clean,  well  managed  cellar,  no  cover  is  needed 
for  the  vats.  If  used  at  all,  it  should  be  removed  as  soon  as  perceptible 
fermentation  commences. 

6.  Stirring.  As  soon  as  the  fermentation  is  evident  the  contents 
of  the  vat  should  be  well  stirred  by  punching  or  pumping  over  at 
least  twice  a  day.  The  objects  are  to  equalize  the  temperature,  to 
promote  extraction  of  color  and  tannin  and  to  aerate  the  must.  Aera- 
tion must  not  be  excessive,  especially  during  the  violent  fermentation 
The  sugar  and  temperature  records  should  be  made  immediately  after 
stirring. 

7.  Cooling. — The  best  red  wines  are  made  when  the  temperature 
does  not  rise  above  90°  F.  Temperatures  above  95°  F.  notably  de- 
crease the  quality.  Where  cooling  devices  are  available,  they  should 
be  used  as  soon  as  or  a  little  before  the  temperature  reaches  90°  F. 
The  amount  of  cooling  necessary  will  depend  on  the  amount  of  sugar 
left,  the  size  of  the  vats  and  the  temperature  of  the  air.  If  the  cooling- 
is  done  when  the  vat  reaches  90°  F.,  the  amount  of  cooling  needed  will 
be  approximately  1.5°  F.  for  each  Bal.  degree  left.  That  is,  a  vat 
which  still  shows  8°  Bal.  when  the  temperature  reaches  90°  F.  should 
be  cooled  about  12  degrees.  This  cooling  may  be  done  in  one  or  two 
operations. 

8.  Drawing-off. — The  time  for  separating  the  wine  from  the  pomace 
by  drawing-off  and  pressing  is  determined  by  the  extraction  of  tannin 
and  color.  The  amount  of  sugar  left  has  nothing  to  do  with  it. 
Fermentation  will  finish  as  well  after  as  before  drawing-off.  The 
maximum  color  is  usually  obtained  after  about  72  hours  of  actual 
fermentation  on  the  skins.  In  hot  fermentations  48  hours  are  sufficient 
for  this  purpose;  in  cold  fermentations  it  may  require  four  or  five 
days.    Siifficicnl  tannin  is  usually  extracted  in  the  same  time,  but  with 


a  few  varieties  of  grapes,  or  if  very  astringent  wines  are  desired,  they 
may  be  left  one  or  two  days  longer  in  the  vat.  In  properly  conducted 
fermentations,  the  time  from  filling  the  vats  to  drawing  off  the  wine 
will  range  between  three  and  five  days. 

9.  After  Fermentation. — When  the  wine  is  drawn  off,  whether  it 
shows  sugar  or  not  by  the  Balling  saccharometer,  it  nearly  always  still 
contains  fermentable  sugar.  The  fermentation  must  not  be  checked, 
but  should  continue  without  interruption  until  completely  finished. 
This  is  accomplished  by  aeration  and  maintaining  the  temperature. 
Drawing-off  stimulates  the  fermentation  by  exposing  the  wine  to  the 
air.  This  is  often  sufficient.  If  not  and  the  wine  still  shows  a  remnant 
of  sugar  to  the  taste  two  days  after  being  placed  in  storage  casks,  it 
should  be  well  aerated  by  pumping  over.  This  aeration  should  be 
repeated  every  two  or  three  days  if  necessary  until  the  wine  has  lost 
all  its  sugar.  In  from  seven  to  fourteen  days  from  crushing,  all  red 
wines  should  be  completely  dry.  During  this  time  the  wine  should 
not  be  allowed  to  become  too  cool.  It  is  well  to  store  it  for  the  after 
fermentation  in  large  casks  in  the  warmest  part  of  the  cellar. 

10.  Removal  of  Yeast. — When  the  wine  is  dry,  the  yeast  has  done 
its  work  and  should  be  removed  as  soon  as  possible.  It  Avill  settle 
completely  in  a  few  weeks  and  the  wine  should  be  racked  off  the 
sediment  into  clean  slightly  sulfured  casks  in  the  coolest  part  of  the 
cellar.  The  smaller  the  casks  the  more  rapidly  and  the  more  perfectly 
the  wine  will  clear  during'  the  winter. 


DIRECTIONS  FOR  DRY  WHITE  WINE  FERMENTATION 

1.  Crushing  and  Pressing. — White  grapes  should  be  a  little  riper 
than  red  and  should  be  crushed  as  cool  as  possible.  Pressing  should 
be  rapid  to  avoid  fermentation. 

2.  Sulfiting. — Somewhat  less  sulfite  is  needed  for  white  than  for 
red  grapes.  A  dose  of  6  ounces  per  ton  is  usually  sufficient.  This 
may  be  increased  to  8,  10,  or  12  ounces  for  sweeter  grapes  or  for  grapes 
in  poor  condition,  and  in  hot  weather.  The  sulfite  is  best  applied  to 
the  crushed  grapes  as  they  run  from  the  crusher. 

3.  Defecation. — The  must  is  first  run  into  a  shallow  settling  vat. 
If  the  crushed  grapes  have  not  been  sulfited,  from  3  to  4  ounces  of 
sulfite  should  be  added  to  each  100  gallons  of  must.  In  closed  casks 
about  2  ounces  of  sulfur  may  be  burnt  per  100  gallons  of  must  instead 
of  using  sulfite.  After  settling  for  24  to  48  hours,  the  clear  must  is 
drawn  off  the  sediment  into  the  fermenting  vats  or  casks.     In  this 


6 

transfer  the  must  should  be  well  aerated  by  allowing  it  to  splash  into 
the  pump  sump. 

4.  Addition  of  Yeast  Starters. — The  yeast  is  added  as  in  red  wine, 
and  as  soon  as  the  must  is  taken  from  the  defecating  vats. 

5.  Records. — At  least  once  a  day  the  sugar  and  temperature  should 
be  tested  and  a  record  made  on  the  outside  of  the  vat  or  cask. 

6.  Cooling  and  Aeration. — The  fermentation  of  white  wine  is  al- 
ways much  slower  than  that  of  red  and  the  temperature  usually  does 
not  rise  so  high.  White  wines,  however,  are  more  easily  injured  by 
high  temperatures  than  red.  The  wine  is  best  if  the  maximum  tem- 
perature does  not  exceed  75°  F.  Where  fermentation  takes  place  in 
puncheons,  no  cooling  is  needed,  as  a  rule.  In  large  casks  or  vats  it 
is  desirable.  Open  vats  for  the  violent  fermentation  are  better  than 
closed,  as  they  allow  more  heat  to  escape. 

7.  After  Fermentation. — The  main  fermentation  will  require  from 
four  to  seven  days,  according  to  the  temperature,  if  a  starter  is  used. 
If  the  wine  is  not  nearly  dry  in  this  time,  it  requires  aeration.  This 
may  be  given  by  pumping  over.  In  from  ten  days  to  three  weeks  the 
wine  should  be  perfectly  dry,  unless  the  temperature  has  been  kept 
very  low.  If  the  last  remnants  of  sugar  are  slow  in  disappearing,  two 
or  three  aerations  by  pumping  over  should  be  given. 

8.  Removal  of  Yeast. — White  wine  is  a  little  slower  in  clearing 
than  red,  but  within  two  or  three  weeks  from  the  time  it  tastes  dry 
it  should  be  racked  from  the  yeast  and  sediment  into  clean,  slightly 
sulfured  casks  and  stored  in  the  coolest  part  of  the  cellar. 

TABLES  OF  AVERAGE  YIELDS 

The  yields  of  the  various  products  of  the  winery  vary  considerably, 
according  to  the  nature  of  the  raw  material  and  of  the  methods  of 
handling.  A  knowledge  of  the  average  yields  and  the  ordinary  varia- 
tions from  these  yields  is  useful  to  the  wine-maker,  as  a  means  of 
testing  the  efficiency  of  his  methods  of  wine  making.  The  following 
data  are  based  on  observations  and  measurements  under  ordinary 
conditions  in  Californian  wineries.  The  data  regarding  quantities  are 
based  on  experiment  and  the  practices  of  the  best  wine-makers. 

Volume  of  a  Ton  of  Grapes 

Maximum 

Fresh  grapes  before  crushing,  cu.  ft 55.66 

Grapes  after  crushing  and  stemming,  cu.  ft.     30.10 

Decrease,  per  cent  59.50%  41.39%  49.50% 


Minimum 

Average 

47.70 

52.43 

21.50 

26.47 

Yields  of  a  Ton  of  Grapes 

Maximum 

Stems  (from  crusher)  64.6  lbs. 

Pomace,  unfermented  513.0  lbs. 

Pomace,  fermented  392.1  lbs. 

Fresh  juice  183.4  gals. 

White  wine,  new  gals. 

White  wine,  after  racking  gals. 

Red  wine,  free  run  143.0  gals. 

Red  wine,  from  press  43.1  gals. 

Red  wine,  total    179.5  gals. 

Red  wine,  after  first  racking  gals. 


Minimum 

Average 

16.2  lbs. 

27.2  lbs. 

265.0  lbs. 

391.0  lbs. 

252.0  lbs. 

345.2  lbs. 

160.4  gals. 

168.7  gals 

gals. 

151.0  gals 

gals. 

145.5  gals 

127.8  gals. 

136.4  gals 

34.7  gals. 

38.4  gals 

170.9  gals. 

174.9  gals 

gals. 

1 69.0  gals 

Temperature  Corrections  for  Balling  Saccharometer 


Observed  T  60 

65 

70 

75 

80 

85 

90 

95 

100 

105 

110  Fahr 

Bal. 

10 

0 

.18 

.35 

.54 

72 

.93 

1.22 

1.47 

1.72 

1.97 

2.22 

11 

0 

.18 

.35 

.54 

72 

.94 

1.22 

1.47 

1.73 

1.98 

2.23 

12 

0 

.19 

.35 

.54 

72 

.94 

1.23 

1.48 

1.73 

1.98 

2.23 

13 

0 

.19 

.36 

.55 

73 

.95 

1.23 

1.49 

1.74 

1.99 

2.24 

14 

0 

.19 

.36 

.55 

73 

.96 

1.24 

1.49 

1.76 

2.00 

2.25 

15 

0 

.19 

.37 

.56 

74 

.97 

.124 

1.50 

1.77 

2.01 

2.26 

16 

0 

20 

.37 

.56 

74 

.98 

1.25 

1.50 

1.77 

2.01 

2.27 

17' 

0 

.20 

.37 

.56 

75 

.98 

1.27 

1.51 

1.78 

2.02 

2.28 

18 

0 

20 

.38 

.57 

75 

.99 

1.28 

1.52 

1.79 

2.03 

2.29 

19 

0 

.20 

.38 

.57 

75 

.99 

1.29 

1.53 

1.79 

2.03 

2.30 

20 

0 

20 

.38 

.58 

76 

.99 

1.30 

1.54 

1.79 

2.04 

2.31 

21 

0 

.20 

.38 

.58 

76 

.99 

1.30 

1.54 

1.80 

2.05 

2.32 

22 

0 

.21 

.39 

.59 

76 

1.00 

1.30 

1.55 

1.80 

2.05 

2.32 

23 

0 

21 

.39 

.59 

77 

1.00 

1.31 

1.55 

1.81 

2.06 

2.33 

24 

0 

.21 

.39 

.59 

77 

1.00 

1.31 

1.56 

1.81 

2.07 

2.34 

25 

0 

21 

.39 

.59 

77 

1.01 

1.32 

1.56 

1.82 

.207 

2.34 

26 

0 

22 

.40 

.60 

78 

1.02 

1.32 

1.57 

1.82 

2.08 

2.35 

27 

0 

.22 

.40 

.60 

78 

1.02 

1.33 

1.57 

1.83 

2.09 

2.36 

28 

0 

.22 

.40 

.60 

79 

1.02 

1.34 

1.58 

1.83 

2.09 

2.36 

29 

0 

.22 

.40 

.61 

80 

1.03 

1.34 

1.58 

1.84 

2.10 

2.37 

Add   the   number   corresponding   to    observed   temperature   to    the   observed 
Balling  degree. 


Approximate  correction : 

For  each  10°  F.  above  60°  F.  add  .4°  Bal. 
For  each  25°  F.  above  60°  F.  add   1°  Bal. 


Balling  and  Sugar  of  Must  and  Alcohol  of  Wine 
(Based  on  Californian  Analyses) 

Balling  Sugar  in  Must  Achohol  in  Wine 

19  18.64  10.9%  by  vol. 

20  19.47  11.5%  by  vol. 

21  20.35  12.0%  by  vol. 

22  21.34  12.5%  by  vol. 

23  22.36  13.2%  by  vol. 

24  23.31  13.8%  by  vol. 

25  24.49  14.5%  by  vol. 

26  25.44  15.1%  by  vol. 

27  26.42  15.6%  by  vol. 

Approximate  estimate.*— Alcohol  by  volume  in  fermented  wine  =  57.5  per  cent 
of  Balling  per  cent  of  must. 


NOTES  ON  WINE  FEEMENTATION 

1.  A  maximum  temperature  of  90°  is  favorable  for  red  wine. 

2.  A  maximum  temperature  of  75°  is  favorable  for  white  wine. 

3.  Sulfurous  acid  is  not  a  means  of  controlling  temperature. 

4.  Potassium    meta -bisulfite    is    about    half    sulfurous    acid,    all    of    which    is 
available. 

5.  Sulfur  when  burned  yields  about  twice  its  weight  of  sulfurous  acid,   only 
half  of  which  is  available  with  the  usual  methods  of  application. 

6.  Sulfurous  acid  added  to  unfermented  must  or  grapes  disappears  rapidly.     It 
disappears  more  slowly  from  fermented  wine. 

7.  In  treating  wine  only  about  one-tenth  the  amount  of  sulfurous  acid  should 
be  used  as  is  used  in  treating  crushed  grapes. 

8.  Sulfurous  acid  prevents  the  action  of  injurious  fermentations.     Pure  yeast 
starters  insure  the  action  of  beneficial  fermentation. 

9.  Aeration  and  heat  stimulate  fermentation. 

10.  The  best  fermentation  is  one  which  continues  without  interruption  until  all 
sugar  has  disappeared. 


